WDPS31 PGTW 131500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 02P (MAL) WARNING NR 
003//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 12.5S 173.2E
   INITIAL INTENSITY: 55 KTS
   GEOGRAPHIC REFERENCE: 451 NM NORTHWEST OF SUVA, FIJI
   MOVEMENT PAST 6 HOURS: SOUTHEASTWARD AT 19 KTS
   SIGNIFICANT WAVE HEIGHT: 28 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A
RAPIDLY DEVELOPING SYSTEM, WITH WELL-FORMED BANDS OF DEEP
CONVECTION WRAPPING INTO AN OBSCURED LOW LEVEL CIRCULATION CENTER
(LLCC). THE MOST RECENT EIR IMAGERY SHOWS INTENSE CONVECTIVE TOWERS
FIRING OFF JUST SOUTHWEST OF THE ASSESSED LLCC, FORMING A SMALL
INNER CENTRAL DENSE OVERCAST (CDO) FEATURE. THE CENTER OF THIS CDO
IS OFFSET WEST-SOUTHWEST DUE TO MODERATE AMOUNTS OF SHEAR IN THE
MID- TO UPPER-LEVELS, WHILE OVERALL DEEP-LAYER SHEAR REMAINS LOW. A
130952Z AMSU-B 89GHZ MICROWAVE IMAGE SHOWED A FORMATIVE EYE, WITH
DEEP CONVECTIVE BANDING FEATURES PRIMARILY EVIDENT ON THE NORTH AND
EASTERN SIDES, HAVING YET TO FULLY CLOSE OFF AN EYE. THE INITIAL
POSITION IS ASSESSED WITH MEDIUM CONFIDENCE DUE TO THE LACK OF
DISTINCTIVE FEATURES IN THE EIR. THE INITIAL INTENSITY IS ASSESSED
WITH HIGH CONFIDENCE BASED ON THE KNES CURRENT INTENSITY ESTIMATE
SUPPORTED BY THE CIMSS ADT, DPRINT AND DMINT ESTIMATES AT 1200Z.
THE SYSTEM CONTINUES TO TRACK QUICKLY TO THE SOUTHEAST ALONG THE
WEST SIDE OF A DEEP-LAYER SUBTROPICAL RIDGE (STR) TO THE EAST.
ENVIRONMENTAL CONDITIONS CONTINUE TO IMPROVE, WITH LOW DEEP-LAYER
VERTICAL WIND SHEAR, WARM SSTS AND STRONG POLEWARD OUTFLOW. THE
ONLY HINDRANCE IS A MODERATE AMOUNT OF VORTEX TILT BROUGHT ON BY
THE MODERATE MID-LEVEL SHEAR FROM THE NORTHEAST.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: WESTERN PERIPHERY OF A DEEP-LAYER STR
CENTERED TO THE EAST. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   KNES: T3.5 - 55 KTS
   PHFO: T2.5 - 35 KTS
   CIMSS ADT: 53 KTS AT 131130Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: STRONG POLEWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   INITIAL INTENSITY: HIGH
   INITIAL WIND RADII: LOW

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: TROPICAL CYCLONE (TC) 02W (MAL) WILL TRACK
SOUTHEASTWARD ALONG THE WESTERN SIDE OF THE STEERING RIDGE THROUGH
THE ENTIRETY OF THE FORECAST PERIOD. SOME SLIGHT DEVIATIONS EAST OR
WEST OF THE FORECAST TRACK ARE POSSIBLE AS THE RIDGE EXPANDS OR
RETREATS AT THE MESOSCALE LEVEL, BUT OVERALL THE TRACK FORECAST IS
STRAIGHT FORWARD. THE SYSTEM IS EXPECTED TO PASS ABOUT 60NM WEST OF
NADI, FIJI BY TAU 24, THEN MOVE INTO THE OPEN WATERS OF THE SOUTH
PACIFIC THROUGH THE REMAINDER OF THE FORECAST. DUE TO A SLOW
RELAXATION OF THE STEERING GRADIENT, THE SYSTEM IS FORECAST TO SLOW
DOWN OVER THE NEXT 48 HOURS BEFORE PICKING UP A BIT MORE SPEED BY
THE END OF THE FORECAST. WHILE THE VORTEX IS STILL TILTED A BIT DUE
TO SOME PERSISTENT MID-LEVEL NORTHEASTERLY SHEAR, GLOBAL MODEL
FIELDS SUGGEST THE SHEAR WILL WEAKEN OVER THE NEXT FEW HOURS, WHICH
SHOULD ALLOW THE CONVECTION SEEN FIRING OFF NOW, TO HELP ALIGN THE
VORTEX. ONCE THIS OCCURS, THE SYSTEM WILL RAPIDLY INTENSIFY THROUGH
TAU 24, REACHING AT LEAST 75 KNOTS AS IT PASSES WEST OF NADI. THE
WINDOW OF OPPORTUNITY FOR INTENSIFICATION WILL BE FLEETING HOWEVER,
WITH SHEAR EXPECTED TO SHARPLY INCREASE BY TAU 36. BY TAU 48, THE
SYSTEM WILL BE WELL INTO COOLER WATERS, WILL BE DECAPITATED BY THE
VERY HIGH WESTERLY SHEAR AND WILL BE IN THE PROCESS OF BEING
SMOTHERED BY VERY DRY MID-LEVEL AIR. THIS WILL MARK THE BEGINNING
OF A RAPID SUBTROPICAL TRANSITION (STT), WHICH WILL BE COMPLETED NO
LATER THAN TAU 72. 

MODEL DISCUSSION: DETERMINISTIC AND ENSEMBLE TRACK GUIDANCE REMAINS
IN VERY GOOD AGREEMENT OVERALL, WITH THE CONTINUED EXCEPTION OF THE
NAVGEM MODEL. DISCARDING NAVGEM, THE REMAINDER OF THE GUIDANCE
PACKAGE IS CONFINED TO AN ENVELOPE WHICH GRADUALLY EXPANDS TO JUST
125NM BY TAU 72. THE JTWC FORECAST REMAINS CONSISTENT WITH THE
PREVIOUS FORECAST AND THE CONSENSUS MEAN WITH HIGH CONFIDENCE.
INTENSITY GUIDANCE IS MIXED, WITH THE MESOSCALE MODELS BACKING OFF
AND SHOWING LITTLE TO NO ADDITIONAL INTENSIFICATION THROUGH THE
FORECAST PERIOD, WHILE THE DECAY-SHIPS (BOTH VERSIONS) ARE THE MOST
AGGRESSIVE OF THE MODELS, TAKING THE SYSTEM UP TO ABOUT 75 KNOTS.
ADDITIONALLY, THE RIPA AND RICN RI AIDS ARE TRIGGERED, PEAKING OUT
AT 95 KNOTS BY TAU 24. THE JTWC FORECAST TRACKS THE GFS SHIPS
GUIDANCE CLOSELY AND THEN REJOINS THE CONSENSUS MEAN BY TAU 48.
CONFIDENCE IS MEDIUM THROUGHOUT THE FORECAST PERIOD DUE TO THE
UNCERTAINTIES SURROUNDING THE POTENTIAL RI. 

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: HIGH
   INTENSITY 0 - 72 HR: MEDIUM//
NNNN